The present disclosure concerns a probe arrangement comprising a distal probe tip and a proximal hand portion for the electrothermal coagulation of tissue. The probe arrangement includes at least a first and a second electrode in the region of the distal probe tip, an inner conductor that extends from the distal probe tip to the proximal hand portion and is adapted to electrically contact the first electrode in the distal probe tip, and an outer conductor which extends from the distal probe tip to the proximal hand portion and is adapted to electrically contact the second electrode in the distal probe tip, wherein the inner and outer conductors are electrically insulated from each other.
Using high-frequency (HF) alternating currents (for example in the frequency range of between 300 KHz and 2 MHz) for the production of high temperatures for tissue coagulation and for tissue separation has long been known in surgery. In arrangements of that kind for bipolar HF-thermotherapy, both electrodes are connected to an HF-generator and are arranged in dimensions that are fixed with each other, for example on an insulating carrier. They are placed by the operator in the immediate proximity of the treatment location and in general are also actively guided.
WO 97/17009 discloses a bipolar electrode arrangement with a liquid duct, by way of which flushing liquid can be introduced into the region of operative intervention. Two or three electrodes are arranged in the form of cone portions on a conical distal tip of the instrument, which can be introduced into the tissue. The electromagnetic HF-field is formed between the electrodes and is intended to coagulate the surrounding tissue.
WO 96/34569 and the documents referred to in the associated International Search Report disclose systems and methods of coagulating body tissue while observing a pre-calculated maximum tissue temperature. Liquid cooling or thermoelectric cooling is provided during the actual tissue coagulation process. These known arrangements are intended for insertion into body cavities by way of natural accesses.
U.S. Pat. No. 4,832,048 and WO 95/10320, WO 99/11186 or EP 96 945 879.3 and WO 98/19613, WO 96/18349 and WO 81/03272 further disclose surgical instruments that, by means of a bipolar electrode arrangement, treat tissue by means of HF-thermotherapy.
WO 00/36985 discloses an electrode arrangement for a surgical instrument for the electrothermal coagulation of tissue. Such an electrode arrangement is shown in FIG. 13. The arrangement has an electrically conductive front cylinder 110 at the distal end of the instrument with a distal tip 112 and a cylindrical first electrode 182, a tubular outer conductor proximally adjoining the front cylinder, with a cylindrical second electrode 184, and an insulator element 170a between the front cylinder 110 and the outer conductor. The electrodes are connectable to an alternating current voltage source.
In that arrangement the first electrode 182 is in the form of a self-supporting tube portion that is disposed between the front cylinder 110 and an insulating tubular first carrier 170a. The second electrode 184 is also in the form of a self-supporting tube portion that is arranged between the first carrier 170a and a second tubular carrier 170b. The end portions of the electrodes 182, 184 rest on the front cylinder 110 and the first and second carriers 170a, b by way of a predetermined longitudinal portion. In addition, within the hollow duct 176 there is a flushing hose 10 that passes from the proximal end of the instrument to the front cylinder and is to say also through the tube portions forming the electrodes. This extends towards the front cylinder 110 and delivers liquid at the distal end into the hollow duct 176 in which the liquid flows back to the proximal end of the instrument. The electrodes 182, 184 are electrically contacted by way of wires 190.
It is also possible to use a cooling fluid for cooling an electrode arrangement. In this connection, that cooling fluid can be gaseous or liquid.
The known surgical instruments for bipolar HF-thermotherapy often suffer from a lack of strength.